Heat-saturation indicator



May 15, 1928. 1,669,510

R. I .FEARN HEAT SATURATION .INDICATOR Filed May 7. 1924 WITNESSES: /Qj mm INVENTOR fch ard L. Fea/n ;ATTORNEY Patented May 15, 1928..

` UNITED STATE-s 'PATENTnOFFICE HEAT-SATBATION INDICATOR.

Appiioauon 'nica my 7,

My invention relates to thermal measuring devices and particularly to means for ilnd methods of determining the transfer of eat.

One object of my invention is to provide a relatively small and simple device for indicating the transfer of heat in a furnace.

Another object of my invention isV toprovide a portable device for insertion into a furnace in which a body is being heated,'

for determinin and indicating' the degree of heat saturation of said body.

It is highly desirable, in the heating of material, particularly when in large masses, to be able to determine when the entire mass has been fully heated.

In practicing my invention, I provide aA A plurality of thermo-couples in' circuit, and arranged to be severall responsive to a source of heat and to the -heat emitting from a body subjected to theheat of said source,- the Vsaid circuit comprising an electricallyresponsive device. When the electricallyresponsive device indicates that both thermof couples generate the same thermal electromotive force,` the body is fully heated. In the single sheet of drawings, Figure 1 is a view of an electric furnace in vertical lateral section, containing a body i to be heated and a thermal measuring device embodying my invention; i

Fi 2 is a top plan view of a thermal respons e device embodying my invention;`

Fig. 3 is a side elevational view thereof; and

Fig. f4 is a phantom perspective view of the arrangement of thermo-couples ernployed in my invention.

A furnace 11 comprises a plurality of refractory walls 12`and a heating means 134 of any well known character, which in the preferred embodiment, comprises an electric heating element. A plurality of heating elements may be used if desired and located in other portions of the furnace structure such as the side and the end walls. The furnace structure thus described is intended to be representative only and to illustrate a furnace with which certain members hereinafter to be described Vmay be operatively associated. c A body 14 to be heated comprising in its composition, material capable of absorb- 1924. Selllal No. 711,708.

ing heat is supported in the furnace chamber and subjected to heat from the heating means 13. Y

An electrically-responsive device 15 suchas an ammeter is connected in circuitwith a thermal-responsive device hereinafter more fully described; the connecting conductors being supported and protected by an 'elongate tubular structure 16.-

The thermally-responsive `device preferably comprises a highly refractory heat insulating member 17, `of substantiallydisk shape, that is supported in a bifurcatedl end of the tubular member 16 and xedlyattached thereto by bolts 18 and 19. The member 16 may be constructed in various ways, but I prefer a simple structure as shown, comprising a plurality of interfitting sections and a handle 20. The arrangement of 4parts issuch that the handle may be 'spaced from the disk 17 any desired distance by the insertion or removal of said sections.

A plurality of thermo-couples are supported upon the disk 17 and separated thereby, and in the preferred embodiment, a pair of thermo-couples 21 and 22 are used, these being connected in circuit with the electrically-responsive device 15 by conductors 23 and 24. The conductors 23 and 24 are `led "to the thermocouples through the tubular member 16 and are maintained in spacedrevlation by a perforated refractory disk member 25. A plurality of such spaced members are mounted in the sections of the member 16 in any suitable manner such as by use of pins 26.

In practice, the thermal-responsive device is inserted into the furnace chamber through one of a plurality of openings 27 in the furnace walls Ythat may be located at convenient points to permit of disposin the device in any desired position relative y to the body being heated. The openings, of course, may be provided with closures (not shown) if desired. Ihave-found it lto be most convenient and practical to interpose the thermal-responsive device between the source of heat and the body being' heated, as it is apparent that there isa temperature difference therebetween resulting in the transfer of heat from the source to the body proportional to the temperature difference. T his vtransfer lof heat increases the temperature refractory plate ofthe thermalv-responsive p direct relation to the degree of heat saturapartin of the body, and the rate of heat emission therefrom increases proportionately. The

device is interposed between 'the source and the body to be heated. The thermocouples are, therefore, subjected to the heat emitting from the source and the body, respectively, which causes electric potentials to be produced in the' thermo-couples and a current to traverse the circuit proportional to their algebraic sum. The electrically-responsive device is actuated in accordance with the amount of current traversing the circuit. It is lapparent, therefore, that the thermal `electromotive force in the thermocouples is proportional to the amount of heat emitted from the heat source and the heated body, respectively, and that the resultant current produced in thecircuit bears a substantially tion of the heated body.

Several ways of utilizing this relation are obvious. If the thermo-couplers are connected in opposed series relation, the current in the circuit will be substantially zero when the heated body has reached su tially the pointA of heat' saturation. An mstrument 15 such as an ammeter, when properly calibrated, will indicate when this point is reached. A suitable control circuit 28 may" be actuated by the current produced .in the thermo-couple circuit, a convenient method.

being to connect the thermo-couples in series circuit relation therewith.

The device embodying my invention thus provides a relativel simple and inexpensive means for determining the heat transfer from a source to a heated body and the degree of heat saturation of the latter.

Various modifications'may bemade in the device embodying my invention without defrointhe s irit and scope thereof, and I esire that onlly such limitations shall be placed thereon as are imposed b the prior art or are specifically set forth 1n the appended claims.

I claim as my invention:

1. The combination with a refractory heat-insulating member, of a pluralit7 of thermo-couples respectively supporte on the two opposite sides thereof, means for electrically connecting the thermo-couples in o position to produce'a resultant thermal e cetro-motive force when subjected simultaneousl tothe tem eratures of a source of heat an of a body lieated thereby, and indicating electro-responsive means connected in circuit with said thermo-cou les.

2. A testing device for a bo y heated by external means, comprising anelectrically- -Aprn 1924.

Lucano responsive device, a 'plurality of thermocouples electrically connected in opposition, means for connecting said thermo-couples in series-circuit relation to said electrically-responsive. device, and arefractory heat insulating member located between said thermocouples for causing said device to be actuated in accordance with the heat emission of the body relatively to the heat emission of the external heating means.-

3. A temperature-ind'cating device for` measuring` the temperature difference between a source of heat and a body to be heated, said device comprising a support'of refractory heat-insulating material, thermocouples located on'e on each side of said support and secured thereto, said support being effective to shield the res ective thermoc'ouples from the sources o heat, affecting the one thermo-couple from the other, an electro-responsive instrument, and means for electrically connecting said 'thermo-couples to said instrument. ,l

4. In combination, a temperature-responsive device for determining the degree of heat transfer from a source-of heat to a body to be heated, said device comprising a therino-couple for measuring the temperature of said source, a thermo-couple for measurin the temperature of said body, means for shieldin the heat affecting the one thermocouple rom the other thermo-couple, said thermo-couples being supported by saidk means, and means for velectrically connecting said thermo-couples.

5. The combination with ,a relatively thin refractory heat insulatin member, of a pair of thermocouples, one t ermo-couple being secured to one flat side of the refractory 1001l member and the other thermo-couple being secured to the other flat side thereof, means for connecting said thermo-couples in opposition in an electric circuit, and a indicating means in said circuit for indicating the difference of electro-motive `forces of the two thermo-couples.

, 6. In a device for measuring the relative heat emission of two thermally related bodies, a relatively thin refractory heat insulating member,ahollow handle secured thereto, a pair of thermocouples secured respectively 'to the opposed lat sides of4 said refractory member, an indicator and conductors traversing said hollow handle for electrically connecting said thermocouples in opposed series circuit relation to said indicator.

In testimony whereof, I have hereunto subscribed my name this thirtieth day of 12( RICHARD L. FEARN. 

